Bioequivalence between ready-to-use recombinant human growth hormone (rhGH) in liquid formulation and rhGH for reconstitution.

The bioequivalence of recombinant human growth hormone (rhGH) for reconstitution, at either 24 IU or 8 mg, and three strengths of liquid formulation of rhGH (5, 10 or 15 mg per 1.5 ml, hGH) was tested in two randomized, single-blind, four-period, crossover studies in healthy subjects. The study drugs were administered by subcutaneous injection at a dose of 2.5 mg rhGH/m(2)body surface area or as a fixed dose of 5 mg rhGH. Endogenous hGH release was suppressed by a continuous somatostatin infusion. The 90% confidence intervals for the estimated mean ratios of AUC(0-24 h)and C(max)(analysis of variance) between all products were within 80-125% in both studies. Also, no significant differences (P> 0.05; Wilcoxon signed rank test) were found between t(max)for the liquid formulations of rhGH. These data demonstrate that there is bioequivalence between rhGH for reconstitution and the liquid formulations of rhGH.     

Potential benefits of recombinant human growth hormone (rhGH) to athletes

Athletes have enjoyed almost a thirty year amnesty of rhGH abuse, which they consider has contributed to the winning of medals and the breaking of world records. Such a reprieve is almost at an end, since WADA have identified a method to detect rhGH abuse. Or have they?The anecdotal word “on the street” is that rhGH is still undetectable and athletes believe that the benefits, at the dosages they administer, far outweigh the risks!Scientists are aware that in a hormone deficiency condition, replacement can halt and in certain situations reverse some of the adverse effects. Growth hormone deficiency can lead to a loss of skeletal muscle mass and an increase in abdomino-visceral obesity, which is reversed on replacement with rhGH.Since the availability of GH, athletes have been trying to extrapolate these effects from the deficiency state to the healthy corpus and increase their sporting prowess.Past confessions from athletes, such as Ben Johnson, Kelly White, Tim Montgomery, Marion Jones and currently Dwain Chambers have demonstrated that they are prepared to tread the very fine lines that separate the “men from the boys”. Rewards are so great, that anonymous surveys have identified that athletes will risk ill health, if they believe they can cheat, win and not get caught.The question that still needs to be answered is, “does growth hormone enhance performance”?Recent research suggests that it could. There is also a suspicion that in “cycled” low supraphysiological doses, it is no where near as harmful as WADA claim it to be.     

Long-term skeletal effects of recombinant human growth hormone (rhGH) alone and rhGH combined with alendronate in GH-deficient adults: a seven-year follow-up study

BACKGROUND: GH-deficient patients respond to recombinant human GH (rhGH) replacement therapy by increasing bone mineral density (BMD) at a rate of about 1% a year for at least 4 years. Predictive factors for a beneficial effect on bone are a low bone mass at baseline and gender. Whether the beneficial skeletal effects of GH are sustained in the long term remains to be established. It is also not known whether osteoporotic GH-deficient patients may require additional antiresorptive drugs and whether this treatment would be effective concomitantly with GH replacement. DESIGN: We performed a long-term, controlled study in 30 GH-deficient adults: 15 with osteoporosis and 15 control subjects with low bone mass. All patients were treated with rhGH for at least 4 years; thereafter, 3 years of additional alendronate treatment was given to patients with osteoporosis, while controls continued on GH therapy alone. The GH dose was individualized to maintain an IGF-I within the normal reference range for the duration of the study, and was equal between genders. RESULTS: At the end of 4 years of rhGH replacement therapy, a significant increase in mean lumbar spine BMD was observed in both the osteoporosis group (3.6%) and the control group (7.0%), with no significant difference between groups. Males had a larger increase in BMD than females (P = 0.032). After 4 or 5 years of GH treatment patients with persisting osteoporosis received additional alendronate (10 mg/day) for 3 years. Lumbar spine BMD increased by 8.7% after 3 years (P = 0.001) vs 1.5% (P = NS) in the control group continuing on rhGH replacement alone. The alendronate effect was gender independent (P = 0.59). Mean bone area of the lumbar spine did not change in both groups for the duration of the study. Femoral neck BMD increased significantly in the osteoporosis group (3.5%) and was unchanged in the control group. Five osteoporotic GH-deficient patients had a total of 12 vertebral fractures before start of alendronate. Only one of these patients developed two new vertebral fractures within the first year of treatment with alendronate. CONCLUSION: We observed a significant increase in lumbar spine BMD in the first 4 years of rhGH replacement. The effect of GH on bone was gender dependent, but not BMD dependent. After more than 4 years of GH replacement, BMD seemed to reach a plateau, at least as measured in the 3-4 years thereafter, as no significant increase was present in patients treated with GH alone. By contrast, alendronate rapidly augmented BMD and this effect was maintained for at least 3 years. These increases in BMD were associated with a low incidence of (vertebral) fractures. The long-term use of GH does not preclude a beneficial effect of an additional antiresorptive agent in GH-deficient patients with osteoporosis.     

The effect of recombinant human growth hormone (rhGH) on trinitrobenzene sulfonic acid-induced colitis in rats: an experimental study

The limited efficacy of standard medical therapies for inflammatory bowel diseases has resulted in a continuing search for alternative treatments. Growth hormone (GH) has shown to have mutagenic and proliferative effects on intestinal cells. This study was designed to identify the effect of growth hormone on trinitrobenzene slfonic acid-induced colitis (TNBSIC) in rats. This study was carried out on 30 rats, divided in 3 groups: group 1: TNBSIC+ GH, group 2: TNBSIC, group 3: saline enema. Colitis was induced in male Sprague-Dawley rats (200 g-250 g) by intracolonic installation of 2, 4, 6-trinitrobenzene sulphonic acid in 50% ethanol. GH treatment has been started and continued throughout the study after inducing colitis. All rats were killed after 5 weeks and colonic segments were examined histopathologically. Microscopic and macroscopic damage scores were caulculated. Intestinal damage scores were found higher in Goups II when compared with treatment group (P < 0.05). There was no damage in group 3 as expected. Both macroscopic and microscopic scores were highest in group 2 (P < 0.05). The myloperoxidase activity was found lower comparing to group 2 (P < 0.05). In conclusion, growth hormone replacement had protective effects against colonic inflammation while reducing intestinal damage on TNB-induced colitis.     

The effect of recombinant human insulin-like growth factor-I treatment on growth hormone secretion in two subjects with growth hormone insensitivity (Laron syndrome)

OBJECTIVE Growth hormone (GH) secretion Is increased in conditions of GH insensitivity such as Laron syndrome, with elevation of both basal and peak levels. We have studied the effect of recombinant IGF-I therapy on the pattern of GH secretion in two subjects with GH insensitivity. SUBJECTS Two pubertal subjects with GH insensitivity (female, 16.4 years, breast stage 3; male 13.6 years, genital stage 2) were investigated after 6 months of IGF-I therapy (120 μg/kg twice daily s.c. at 0800 and 1900 h). GH profiles taken before the start of IGF-I therapy, when both subjects were prepubertal (aged 14 0 and 11 5 years respectively), were used for comparison. METHODS GH profiles were performed with blood samples taken every 20 minutes between 2000 and 0800 h from an indwelling cannula. MEASUREMENTS Serum samples were assayed for GH by immunoradiometric assay and IGF-I, IGFBP-1 and insulin by radioimmunoassay. RESULTS Before IGF-I therapy, GH profile studies demonstrated pulsatile GH secretion. Basal GH was elevated with no value falling below the limit of detection of the assay and an increase in peak levels (maximum 203 and 206 μ/I at 0000 h and 0020 h respectively). After 6 months IGF-I therapy, the GH profiles were significantly different. With the onset of puberty a further increase in GH secretion would have been expected; nevertheless, following administration of IGF-I at 1900 h, GH secretion decreased with a reduction in mean overnight GH levels from 65 to 33 μ/l and 53 to 11 μ/l respectively. GH pulsatility was also suppressed in the two subjects, for the first 3.5 and 6 hours overnight respectively. Pulsatile GH secretion then returned with peak levels reaching 130 and 63 μ/l respectively. Prior to therapy IGF-I levels were at the lower limit of assay detection. On IGF-I therapy serum IGF-I levels reached a peak within 3 hours (298 and 438 μg/l) coinciding with the suppression of GH secretion. IGF-I levels fell rapidly overnight to 92 and 101 μg/l at 0800 h prior to the next injection. The fall in serum IGF-I coincided with the return of GH secretion. IGFBP-1 levels increased overnight both before and during IGF-I therapy, rising from 24 to 83 and 22 to 110 μg/l before therapy and 13 to 60 and 13 to 71 μg/l during therapy. This rise in IGFBP-1 appeared to be inversely related to the fall in serum insulin levels overnight and appeared not to be affected by IGF-I therapy. CONCLUSION GH secretion is suppressed by exogenous IGF-I therapy in GH insensitive subjects. The failure to maintain high serum IGF-I levels overnight, presumably due to a persisting defect in serum IGFBP-3 levels, was associated with an early return of GH secretion. These findings may have implications for the dose and regimen of IGF-I therapy in subjects with growth hormone insensitivity.     

The effect of synthetic human pancreatic growth hormone-releasing factor (hpGRF-44) on serum growth hormone response in normal and obese subjects

Synthetic human pancreatic growth hormone-releasing factor (hpGRF-44) was given by i.v. bolus injection to 15 normal non-obese and 32 obese subjects who were divided into two groups according to their ages--group A: young subjects, 20-50 yrs., and group B: old subjects, more than 60 yrs. In normal subjects, hpGRF-44 had no effect on the secretion of PRL, TSH, LH, FSH, IRI and cortisol. hpGRF-44 stimulated GH secretion selectively. However, the serum GH responses were different between the young and old groups, the peak GH levels being significantly higher in the young group than in the old group (20.1 +/- 4.2 vs. 7.5 +/- 1.6 ng/ml; group A vs. B; p less than 0.05). At the doses of 0.5, 1.0, 2.0 and 4.0 micrograms/kg B.W., the serum GH responses were similar in an individual subject. In young obese subjects, the peak GH levels to hgGRF-44, 1.0 microgram/kg B.W. were significantly lower than those in young normal subjects (4.3 +/- 0.6 vs. 20.1 +/- 4.2 ng/ml; obese vs. normal; p less than 0.01). In old subjects, the peak GH levels to hpGRF-44, 1.0 microgram/kg B.W. were similarly diminished in both normal and obese subjects. However, the integrated response of GH was significantly lower in obese subjects than in normal subjects (405.9 +/- 58.7 vs. 755.9 +/- 134.2 ng X min/ml; obese vs. normal; p less than 0.05). In 5 young obese subjects, regular insulin (RI) injection (0.15 U/kg B.W.) and arginine drip infusion (0.5 g/kg B.W.) alone, and simultaneous injection of hpGRF-44, 1.0 microgram/kg B.W. and RI, 0.15 U/kg B.W. were done. In these subjects, GH responses to RI or arginine infusion were diminished as in the case of hpGRF-44 administration, whereas the peak GH levels were higher in the RI stimulation. The combination of hpGRF-44 and RI partially restored GH response. (peak GH levels; 14.6 +/- 0.8 ng/ml). These results confirm the age difference of serum GH response to hpGRF-44 and also indicate that obese subjects show low or no response to hpGRF-44 administration. The fact that insulin hypoglycemia induced larger serum GH response that hpGRF-44 in obese subjects may suggest the existence of GH-releasing substances other than hpGRF-44.     

The effects of 10 years of recombinant human growth hormone (GH) in adult GH-deficient patients.

The long term effects of GH replacement in adult GH-deficient (GHD) patients have not yet been clarified. We studied 21 GHD adults who originally took part in a randomized, double blind, placebo-controlled trial of GH treatment in 1987. After completion of that trial, 10 patients received continuous GH replacement for the subsequent 10 yr, whereas 11 did not. A group of 11 age- and sex-matched normal controls were also studied in 1987 and 1997. Lean body mass, as assessed by total body potassium measurement and computed tomography scanning of the dominant thigh, increased in the GH-treated group (P < 0.01 for both) only (P < 0.05 between groups for total body potassium). Low density lipoprotein cholesterol decreased in the GH-treated group (P < 0.05) only. Carotid intima media thickness was significantly greater (P < 0.05) in the untreated group than in the GH-treated group. Assessment of psychological well-being using the Nottingham Health Profile revealed improvement in overall score, energy levels, and emotional reaction in the GH-treated group compared with those in the untreated group (P < 0.02). In conclusion, GH treatment for 10 yr in GHD adults resulted in increased lean body and muscle mass, a less atherogenic lipid profile, reduced carotid intima media thickness, and improved psychological well-being.     

Use of recombinant human growth hormone (rhGH) plus recombinant human granulocyte colony-stimulating factor (rhG-CSF) for the mobilization and collection of CD34+ cells in poor mobilizers

The activity of recombinant human growth hormone (rhGH) in enhancing CD34(+) cell mobilization elicited by chemotherapy plus recombinant human granulocyte colony-stimulating factor (rhG-CSF) was evaluated in 16 hard-to-mobilize patients, that is, those achieving a peak of circulating CD34+ cells 10/microL or less, or a collection of CD34(+) cells equal to or less than 2 x 10(6)/kg. Patients who had failed a first mobilization attempt with chemotherapy plus rhG-CSF (5 microg/kg/d) were remobilized with chemotherapy plus rhG-CSF and rhGH (100 microg/kg/d). As compared with rhG-CSF, the combined rhGH/rhG-CSF treatment induced significantly higher (P < or =.05) median peak values for CD34(+) cells/microL (7 versus 29), colony-forming cells (CFCs)/mL (2154 versus 28,510), and long-term culture-initiating cells (LTC-ICs)/mL (25 versus 511). Following rhG-CSF and rhGH/rhG-CSF, the median yields of CD34(+) cells per leukapheresis were 1.1 x 10(6)/kg and 2.3 x 10(6)/kg (P < or =.008), respectively; the median total collections of CD34(+) cells were 1.1 x 10(6)/kg and 6 x 10(6)/kg (P < or =.008), respectively. No specific side effect could be ascribed to rhGH, except a transient hyperglycemia occurring in 2 patients. Reinfusion of rhGH/rhG-CSF-mobilized cells following myeloablative therapy resulted in prompt hematopoietic recovery. In conclusion, our data demonstrate that in poor mobilizers addition of rhGH to rhG-CSF allows the patients to efficiently mobilize and collect CD34(+) cells with maintained functional properties.     

Influence of pyridostigmine on growth hormone (GH) response to GH-releasing hormone pre- and postprandially in normal and obese subjects.

The effect of pyridostigmine (PYR), an inhibitor of acetylcholinesterase, on the GH response to GH-releasing hormone (GHRH) before and after a meal was studied in 14 normal subjects (8 females and 6 males) and 21 obese subjects (13 females and 8 males). In normal subjects tested in a fasting state, PYR was capable of stimulating GH secretion and increasing the GH response to GHRH. These effects were not apparent after food, suggesting a reduction in cholinergic hypothalamic activity. In obese subjects tested in a fasting state, PYR was ineffective when administered alone. On the contrary, it was able to increase the GH response to GHRH. After food, the augmenting effect of PYR on the GH response to GHRH was not observed, whereas a delayed inhibition of the GH response was found after PYR plus GHRH treatment. Our findings support the hypothesis that cholinergic hypothalamic activity plays a pivotal role in impaired GH regulation and the altered sensitivity of GH secretion to metabolic fuels in obese subjects.     

Regulation of growth hormone (GH) bioactivity by a recombinant human GH-binding protein

The in vitro biological effects of serum GH-binding protein (GHBP) were measured in the mouse 3T3-F442A preadipocyte adipogenesis assay during GH stimulation. Coincubation of increasing concentrations of human (h) GH (0.14-4.5 nM) with 4.2 nM recombinant hGHBP-(1-247) in serum-free medium shifted the hGH dose-response curve to the right over the range 0.14-0.9 nM. When the hGH concentration was fixed at 0.45 nM, a dose-dependent inhibition of GH bioactivity was seen over the range of 0.1-11.3 nM GHBP, with an ED50 of 3 nM. The presence of serum had no effect on the inhibitory properties of GHBP. When 2% pooled human serum was added to incubation medium containing 0.45 nM hGH and GHBP (0.6 nM-5.7 nM), the effect of GHBP was again inhibitory, with an ED50 of 1.2 nM. Two percent serum alone was adipogenic, but at this low serum concentration it is likely that some factor other than GH is responsible. In a homologous receptor assay, the binding of [125I]hGH to IM-9 lymphocytes was inhibited in a dose-dependent manner by increasing concentrations of hGHBP in the physiological range, providing further support for the idea that GHBP can regulate the bioactivity of GH by blocking the binding of free GH to target tissues in vivo. Our results suggest that one function of GHBP is to dampen the biological effects of pulsatile GH secretion by reducing free GH during secretory pulses. This effect combined with an increased half-life of circulating GH would have the effect of flattening the hormone secretory profile at the target tissue level.     

Effect of long-term administration of recombinant human growth hormone (rhGH) on plasma erythropoietin (EPO) and haemoglobin levels in anaemic patients with adult GH deficiency

OBJECTIVE: We investigated the effect of recombinant human GH (rhGH) on erythropoietin (EPO) and haemoglobin (Hb) concentrations in anaemic patients with adult GH deficiency. PATIENTS AND DESIGN: rhGH was administrated in 8 patients with adult GH deficiency, three males and five females, aged from 24 to 69 years, mean (+/- SD) of 48.8 +/- 16.4 years, for 1 year by means of continuous subcutaneous infusion (CSI) at a flow rate of 0.036 U/kg/day using a portable syringe pump. Blood samples were obtained in the morning after an overnight fast every week for 1 month, followed by each month before and after the start of rhGH administration. RESULTS: Mean (+/- SE) plasma GH levels increased from 0.24 +/- 0.09 microg/l to 2.32 +/- 0.23 microg/l 1 week after the start of rhGH administration to maintain a steady state. Plasma IGF-I levels increased from 70.1 +/- 13.8 microg/l to 282.8 +/- 70.6 microg/l 1 week after the start of rhGH administration to maintain the steady state. Plasma EPO levels increased from 25.9 +/- 2.6 IU/l to 37.6 +/- 4.2 IU/l and 34.3 +/- 3.6 IU/l at 1 week and 2 weeks after the start of rhGH administration, respectively, and then decreased gradually to 14-9 +/- 2.1 IU/l at 10 months after the start of rhGH administration. Reticulocyte counts increased from 0.88 +/- 0.06% to 1.49 +/- 0.21% at 1 week. Hb concentrations increased from 103 +/- 5 g/l to 106 +/- 5 g/l at 2 weeks after the start of rhGH administration, and then increased gradually to reach the normal range. CONCLUSIONS: We conclude that EPO secretion was stimulated in the initial 2 weeks after the start of CSI of rhGH in anaemic patients with adult GH deficiency. Increased Hb concentrations after long-term administration of rhGH might be explained by direct stimulatory effects of rhGH and IGF-I on erythroid cells, which was accompanied by suppressed EPO secretion, in combination with a more generalized indirect impact of rhGH on physical activety. These findings suggest a beneficial effect of rhGH replacement in anaemic patients with adult GH deficiency.     

Acute effects of growth hormone on vascular function in human subjects

GH is involved in the long-term regulation of peripheral vascular resistance and vascular reactivity. We determined whether GH plays a role in the acute regulation of vascular function in humans. The acute vascular effects of GH were studied in eight healthy subjects according to a double-blind, placebo-controlled design. Forearm blood flow (FBF), vascular resistance, and nitric oxide (NO) production were monitored during a 4-h infusion of GH into the brachial artery at a rate chosen to raise local GH to stress levels (approximately 40 ng/ml). During GH infusion, FBF rose 75% (P < 0.05), whereas forearm vascular resistance decreased comparably (P < 0.05). These changes were paralleled by augmented forearm release of NO (P < 0.02). GH heightened the response of FBF to the endothelium-dependent vasodilator acetylcholine (Ach; P < 0.02). With the highest Ach dose, FBF reached 30.4 +/- 4.2 and 16.9 +/- 3.1 ml/dl x min in the GH and placebo studies, respectively (P < 0.005). The slopes of the dose-response curves also differed markedly (0.45 +/- 0.07 and 0.25 +/- 0.05 ml/dl x min/ microg in the GH and placebo studies, respectively; P < 0.01). GH caused an upward shift of the FBF response to the endothelium-independent vasodilator sodium nitroprusside (P < 0.01), but did not affect the slope of the dose-response curve. GH infusion did not cause any appreciable increment in the venous IGF-I concentration in the test arm. In conclusion, GH acutely lowers peripheral vascular resistance and stimulates endothelial function. These effects are mediated by activation of the NO pathway and appear to be independent of IGF-I.     

Corticosteroid-induced growth hormone secretion in normal and obese subjects

OBJECTIVE: In normal subjects, corticosteroids stimulate growth hormone (GH) secretion at 3 hours. Obesity is associated with blunted GH secretion. In order to clarify both the deranged mechanism of GH secretion in obesity and the corticosteroid mechanism of action we have assessed in normal and obese subjects the effects of dexamethasone, pyridostigmine (a drug capable of suppressing somatostatin release) and GHRH. We also compared in normal subjects the stimulatory effect of three different corticosteroids on plasma GH levels. DESIGN: In both normal and obese subjects the following tests were carried out: placebo; dexamethasone alone (4 mg i.v. at 0 minutes); and dexamethasone plus pyridostigmine (120 mg p.o. at 60 minutes). In normal subjects we also studied the effects of hydrocortisone (100 mg i.v. at 0 minutes) and deflazacort (a corticosteroid that does not cross the blood-brain barrier) (60 mg i.v. at 0 minutes). In obese subjects we also assessed the effect of dexamethasone plus GHRH (100 micrograms i.v. at 150 minutes) on plasma GH levels. PATIENTS: Ten normal subjects and 22 obese subjects were studied. Normal controls were within 10% of their ideal body weight. Obese subjects had a body mass index of 37.1 +/- 1.1 (mean +/- SEM). MEASUREMENTS: Plasma GH levels were measured by radioimmunoassay. RESULTS: Dexamethasone-induced GH secretion in normal subjects (28.6 +/- 7.8 millimicron/l, P less than 0.05). Corticosteroids did not alter GH levels in obese subjects. Pretreatment with pyridostigmine increased dexamethasone-induced GH release in normal subjects (40.8 +/- 6.8 millimicron/l) but this did not achieve statistical significance. Dexamethasone plus pyridostigmine did not alter GH levels in obese subjects (8.0 +/- 1.6 mU/l). In some subjects, dexamethasone pretreatment potentiated GHRH-stimulated GH secretion, while in half the subjects the basal GH levels were not altered. In control subjects, hydrocortisone and deflazacort caused GH release similar to dexamethasone. CONCLUSIONS: Corticosteroids are a new and selective stimulus of GH secretion. They do not cause GH release in obese subjects. Their relative independence from cholinergic control suggest that they act by reducing somatostatin secretion.     

The effect of pegylated recombinant human leptin (PEG-OB) on weight loss and inflammatory status in obese subjects

OBJECTIVE: To investigate whether weekly subcutaneous administration of 60 mg of long-acting pegylated human leptin (PEG-OB) for 8 weeks was able to influence weight loss, metabolic profile and inflammatory status of obese subjects on a mildly hypoenergetic diet (deficit: 3.2 MJ/day). DESIGN: A prospective, randomized, double-blind and placebo-controlled single-center trial. SUBJECTS: Twenty-eight healthy, obese subjects (16 women, 12 men; age 22-65 y; body mass index 27.7-38.7 kg/m2). MEASUREMENTS: Bodyweight, metabolic profile (including lipids), C-reactive protein (CRP) and soluble TNF alpha-receptor (sTNF-R) 55 and 75 levels. RESULTS: At the end of the study no significant differences in the delta or percentage weight loss between the placebo (n = 14) and PEG-OB (n = 14) groups was observed. Also the changes in metabolic profile, CRP, sTNF-R55 and R75 concentrations between the two groups after 8 weeks of treatment did not differ. CONCLUSION: Weekly injection of 60 mg PEG-OB did not lead to additional weight loss after 8 weeks of treatment. Furthermore, PEG-OB administration did not affect the changes in metabolic profile and the inflammatory status of obese subjects.     

Protective effects of recombinant human growth hormone on cirrhotic rats

AIM: To investigate the effects and molecular mechanisms of recombinant human growth hormone (rhGH) on protecting liver function and alleviating portal hypertension of liver cirrhotic rats. METHODS: Liver cirrhosis of male Sprague-Dawley rats was induced by administration of thioacetamide. The rats with or without liver cirrhosis were randomly divided into four groups. Group A consisted of the normal rats was treated with normal saline (NS), group B consisted of the normal rats was treated with rhGH, group C consisted of cirrhotic rats was treated with NS, and group D consisted of cirrhotic rats was treated with rhGH. The rats of different groups were subcutaneously injected with 0.5 mL of NS or 333 ng/kg of rhGH daily for 7 d. After treatments, the following parameters were examined, including GH-binding capacity (R(T)) by (125)I-hGH binding, growth hormone receptor mRNA(GHR mRNA) expression by RT-PCR, relative content of collagen (RCC) by histomorphomertry, and level of malon-dialdehyde (MDA) and superoxide dismutase (SOD) in liver tissue by thiobarbituric acid reaction and pyrogallic acid self-oxidation, respectively. Serum albumin (ALB), alanine transaminase (ALT) and portal vein pressure (PVP) were also examined. RESULTS: rhGH up-regulated both the GH-binding capacity (R(T)) and the expression of GHR mRNA in vivo. R(T) in group A (72+/-12 fmol/mg protein) was significantly higher than that in group C (31+/-4 fmol/mg protein) (P<0.05). R(T) in group B (80+/-9 fmol/mg protein) increased markedly compared to group A (P<0.05). R(T) in group D (40+/-7 fmol/mg protein) raised remarkably compared with group C (P<0.05), but less than that in group A, and there was no significant GH binding affinity contrast (Kd) change. The GHR mRNA level (iOD, pixel) in group A (29+/-3) was significantly higher than that in group C (23+/-3) (P<0.05). GHR mRNA levels were significantly raised in group B (56+/-4) and group D (42+/-8) compared with groups A and C (29+/-3 and 23+/-3, respectively) (P<0.05). Compared with the normal liver, MDA level was higher and SOD level was lower in cirrhotic livers. After rhGH treatment, MDA level was significantly declined to 12.0+/-2.2 nmol/mg protein and SOD was raised to 1 029+/-76 U/mg protein in group D (P<0.05). ALB levels in groups B and D (42+/-7 g/L and 37+/-7 g/L, respectively) were significantly raised compared with those in groups A and C (35+/-5 g/L and 29+/-4 g/L, respectively) (P<0.05). ALT level was markedly lower in group D (69+/-7 U/L) compared to group C (89+/-15 U/L) (P<0.05), and close to group A (61+/-10 U/L). RCC in group C (22.30+/-3.86%) was significantly higher than that in group A (1.14+/-0.21%) and group D (14.70+/-2.07%) (P<0.05). In addition, rhGH markedly alleviated portal hypertension in liver cirrhotic rats (group D vs C, 9.3+/-1.5 cmH(2)O vs 14.4+/-2.0 cmH(2)O) (P<0.05). CONCLUSION: Pharmacological doses of rhGH can increase R(T) and GHR mRNA expression, ameliorate liver functions, repress fibrosis and decline portal hypertension, suggesting it has potentially clinical usage as a hepatotropic factor.     

Enhanced growth hormone (GH) responsiveness to GH-releasing hormone after dietary manipulation in obese and nonobese subjects

Changes in plasma GH responses to GHRH (1 microgram/kg, iv) were assessed after dietary manipulations in obese and nonobese subjects to determine whether the impaired GH responsiveness to GHRH in obesity is the consequence of obesity per se or of altered food intake. The mean plasma GH response to GHRH in 10 obese subjects was significantly (P less than 0.05) higher after a 72-h fast than when they were eating their usual diet. Comparable increases were found when 6 of the subjects were studied after eating an 800 Cal/day diet for 6 weeks (P less than 0.05). Plasma glucose and insulin levels were lower and FFA levels higher after fasting, but not after the diet, compared to values on the usual diet. The mean plasma somatomedin-C (Sm-C) level was similar to that in nonobese subjects and was unaffected by dietary changes. The peak GH responses to GHRH before fasting were inversely correlated with plasma Sm-C levels (r = 0.64; P less than 0.05). Plasma GH responses to GHRH in normal weight subjects were also higher after fasting for 24 h (P less than 0.05) and 72 h (P less than 0.01) than after an overnight fast. Plasma glucose, insulin, and FFA changes were similar in the obese and normal weight subjects. Plasma Sm-C levels in the nonobese subjects were slightly lower after 72 h of fasting. We conclude that the increased plasma GH responsiveness to GHRH after fasting is not unique to obesity and is unlikely to reflect a reversal of the obesity-associated impairment of GH secretion. The increased plasma GH responsiveness to GHRH after as little as 24 h of fasting suggests that it is a consequence of acute nutrient deprivation rather than weight loss. The enhanced responses in obese subjects after 6 weeks of food restriction, in contrast, are probably a consequence of weight reduction.     

Elevated insulin levels contribute to the reduced growth hormone (GH) response to GH-releasing hormone in obese subjects.

We have recently presented experimental evidence indicating that insulin has a physiologic inhibitory effect on growth hormone (GH) release in healthy humans. The aim of the present study was to determine whether in obesity, which is characterized by hyperinsulinemia and blunted GH release, insulin contributes to the GH defect. To this aim, we used a simplified experimental protocol previously used in healthy humans to isolate the effect of insulin by removing the interference of free fatty acids (FFAs), which are known to block GH release. Six obese subjects (four men and two women; age, 30.8 +/- 5.2 years; body mass index, 36.8 +/- 2.8 kg/m2 [mean +/- SE]) and six normal subjects (four men and two women; age, 25.8 +/- 1.9 years; body mass index, 22.7 +/- 1.1 kg/m2) received intravenous (i.v.) GH-releasing hormone (GHRH) 0.6 microg/kg under three experimental conditions: (1) i.v. 0.9% NaCl infusion and oral placebo, (2) i.v. 0.9% NaCl infusion and oral acipimox, an antilipolytic agent able to reduce FFA levels (250 mg at 6 and 2 hours before GHRH), and (3) euglycemic-hyperinsulinemic clamp (insulin infusion rate, 0.4 mU x kg(-1) x min(-1)). As expected, after placebo, the GH response to GHRH was lower for obese subjects versus normals (488 +/- 139 v 1,755 +/- 412 microg/L x 120 min, P < .05). Acipimox markedly reduced FFA levels and produced a mild reduction of insulin levels; under these conditions, the GH response to GHRH was increased in both groups, remaining lower in obese versus normal subjects (1,842 +/- 360 v 4,871 +/- 1,286 microg/L x 120 min, P < .05). In both groups, insulin infusion yielded insulin levels usually observed under postprandial conditions and reduced circulating FFA to the levels observed after acipimox administration. Again, the GH response to GHRH was lower for obese subjects versus normals (380 +/- 40 v 1,075 +/- 206 microg/L x 120 min, P < .05), and in both groups, it was significantly lower than the corresponding response after acipimox. In obese subjects, as previously reported in normals, the GH response to GHRH was inversely correlated with the mean serum insulin (r = -.70, P < .01). In conclusion, our data indicate that in the obese, as in normal subjects, the GH response to GHRH is a function of insulin levels. The finding that after both the acipimox treatment and the insulin clamp the obese still show higher insulin levels and a lower GH response to GHRH than normal subjects suggests that hyperinsulinemia is a major determinant of the reduced GH release associated with obesity.     

Cardiovascular risk evaluated by C-reactive protein levels in diabetic and obese Mexican subjects.

BACKGROUND: Previous studies have reported elevated levels of C-reactive protein (CRP) in obese and diabetic subjects, but it is unclear whether both these conditions have an additive effect on the variability of serum CRP levels. METHODS AND RESULTS: The study enrolled 385 men and women who were classified into 4 groups: (1) diabetes (n=97), (2) obesity (n=108), (3) diabetes/obesity (n=78), and (4) healthy (n=102). All were Mexican subjects from Guerrero State. Serum high-sensitivity CRP (hs-CRP) levels were higher in both type 2 diabetes mellitus (T2DM)/obesity and obesity (5.1 mg/L) groups than in the diabetics (1.8 mg/L) without obesity. Only the measurements of obesity were strongly related to hs-CRP (body mass index, r=0.46 and waist circumference, r=0.41). The presence of T2DM and obesity explain 20% of the circulating hs-CRP level, following waist circumference (16%), leukocyte count (10%), diastolic blood pressure (6%), and female gender (4%). Obese subjects (odds ratio (OR)=6.3) and T2DM/obesity patients (OR=6.9) showed high risk for coronary disease and this effect was increased in T2DM/obesity women (OR=9.9). Also, abdominal obesity was associated with high coronary disease risk (OR=5.4), showing an increase in women (OR=7.3). CONCLUSION: High hs-CRP levels are related to obesity and central distribution of body fat, leading to a higher cardiovascular risk among Mexican subjects.     

The effect of orlistat-induced weight loss on interleukin-6 and C-reactive protein levels in obese subjects

OBJECTIVE: Inflammation plays a major role in the pathogenesis of atherosclerosis. Obesity is an independent risk factor for cardiovascular disease, which may be mediated by increased secretion of proinflammatory cytokines by adipose tissue. The aim of this study is to investigate changes in the inflammatory markers interleukin-6 (IL-6) and high-sensitivity C-reactive protein (hs-CRP) during weight reduction with orlistat treatment in obese patients. METHODS AND RESULTS: Thirty-six obese (BMI: 36.1 +/- 3.4 kg/m2) and II non-obese (BMI: 22.9 +/- 1.7 kg/m2) subjects were studied. IL-6 and hs-CRP levels were evaluated at baseline. In obese subjects after treatment of orlistat 120 mg three times daily for 6 months, IL-6 and hs-CRP levels were repeated. Levels of circulating IL-6 (p < 0.05) and hs-CRP (p < 0.01) were significantly higher in the obese group than in the non-obese group. Plasma IL-6 (r = 0.29 and p < 0.05) and CRP (r = 0.35 and p < 0.05) concentrations correlated positively with the level of obesity assessed by BMI at baseline. After 6 months of orlistat treatment in obese subjects, the mean weight of the patients decreased by 6.8 kg, the BMI by 3.2 kg/m2. Compared with baseline, weight loss was associated with significant reductions of IL-6 (p < 0.001) and hs-CRP (p < 0.001) levels. CONCLUSION: In summary plasma IL-6 and hs-CRP levels were increased in obese patients. Orlistat-induced weight reduction was associated with decreasing levels of both IL-6 and hs-CRP in obese subjects. Because inflammatory mediators may be directly involved in atherogenesis, this would suggest that interventions to reduce IL-6 and CRP levels could be cardioprotective.